Embodiments relate to an electronic device, including a CMOS image sensor. Some embodiments relate to a method of fabricating a CMOS image sensor.
Image sensors may be semiconductor devices, and may be used to change an optical image into an electrical signal. Image sensors may be categorized as a Charge Coupled Device (CCD). A CCD may have a structure in which MOS capacitors are disposed adjacent relative to each other. Charge carriers in a CCD may be stored in a MOS capacitor and may be transmitted to another MOS capacitor, for example at a rear end thereof However, a CCD may have a relatively complicated driving method, high power consumption, and/or complicated fabrication process due to several steps that may be involved in a photo process. Since it may be relatively difficult to integrate a control circuit, a signal processing circuit, and/or an A/D converter circuit into a CCD chip, a CCD may cause difficulty in product miniaturization.
An image sensor may be categorized as a Complementary Metal-Oxide-Silicon (CMOS) image sensor. Recently, a CMOS image sensor has been investigated to address one or more drawbacks related to a CCD. A CMOS image sensor may employ a switching manner, in which MOS transistors corresponding to a number of unit pixels are formed over a semiconductor substrate through a CMOS technique. A control circuit and a signal processing circuit may be used as peripheral circuits, and outputs of respective unit pixels may be sequentially detected by MOS transistors. A CMOS image sensor may form a photodiode and a MOS transistor in each unit pixel, and thus may sequentially detect electrical signals of respective unit pixels in a switching manner, thereby implementing an image.
A CMOS image sensor may use a CMOS technique, and may have a relatively low power consumption and/or simple fabrication process due to a relatively small number of steps that may be involved in a photo process. Since a control circuit, a signal processing circuit, and/or an A/D converter circuit may be integrated into a CMOS image sensor chip, a CMOS image sensor may facilitate product miniaturization. A CMOS image sensor may be widely used in various fields, such as digital still cameras and digital video cameras.
However, in a CMOS image sensor, electrons generated by light may easily disappear due to a relatively shortened life span. It may be difficult to transmit electrons generated from relatively deep inside of a photodiode, for example to a transfer gate. Thus, there is a need for a CMOS image sensor, and/or a method of fabricating a CMOS image sensor, which may minimize the disappearance of electrons generated by light without transmission of the electrons to a transfer gate.